L9110 HG7881 Dual Channel Stepper Motor Driver Board
This is a dual channel stepper motor driver controller board, which can control two DC motors, or a single four-wire two-phase stepper motor. The circuit uses the L9110 (HG7881) integrated circuits (IC), which consist of H-Bridge drivers.
L9110S
The L9110S IC has TTL / CMOS compatible I/O, which interfaces with Arduino and Raspberry Pi computer boards. A minimum of 2.5 V is required to represent a high logic at the inputs IA and IB. The voltage that you provide to power the IC is the same as that which powers the motor. Hence, this IC operates on a wide supply range (Vcc) from 2.5 V to 12 V. If you were to be using 6 V motors, then obviously, that is the voltage to provide the IC.
This IC provides up to 800 mA continuous drives current to drive a load, however it does not have a heatsink, making it more suitable for low power loads. If you draw more current through it, then it will start to heat up and smoke. Its maximum operating temperature is 80 ºC, and power dissipation is critical. It has a rated peak current of 1.5 A to 2.0 A, however, this is fine for short bursts only, and maintaining it for any length of time will probably result in damage to the IC. An advantage of this IC is that it has built-in clamping diodes for back EMF protection, which eliminates the external component count to only the IC and motor.
Pinout / PWM
This is ideal for toy car applications where an H bridge provides forward and reverse controls to the motor.
To control the speed of the motor shaft, pulse-width modulation (PWM) techniques are required; however, I would recommend very low power loads when employing this because this IC does not have any way to dissipate the heat energy generated.
When using PWM, you simply apply the width-modulated signal to the input IA, whilst the secondary input IB provides direction (forward / reverse) control.
Board / Module
The manufacturing is to a high standard, and the surface-mount device (SMD) component placement is accurate. This is a very small board and measures approximately 25 mm × 20 mm, making it ideal to fit inside a toy robot or a small car.
Screw Terminals
Review
I bought this to control the motors on the bigtrak toy car and it works fine as it is a battery-powered application. I made a slight modification by attaching the board using the centre hole to a heatsink so that the two driver chips were in tight contact with it.
These boards are available from eBay and Amazon at varying prices. I bought the cheapest one on eBay for less than one pound including postage and it came from China two weeks later.